flake: add u-boot and fsbl

flake.nix

@@ -1,9 +1,56 @@
 {
   description = "Not-OS port to the Zynq-7000 platform";
   
+  inputs.nixpkgs.url = github:NixOS/nixpkgs/nixos-unstable;
   inputs.not-os.url = github:cleverca22/not-os;
+  inputs.zynq-rs.url = git+https://git.m-labs.hk/m-labs/zynq-rs;
+  
+  outputs = { self, nixpkgs, not-os, zynq-rs }:
+    let
+      pkgs = import nixpkgs { system = "x86_64-linux"; };
+      zynqpkgs = zynq-rs.packages.x86_64-linux;
+
+      build = { target ? "zc706" }: let 
+        fsbl = zynqpkgs."${target}-fsbl";
+
+        u-boot = pkgs.pkgsCross.armv7l-hf-multiplatform.buildUBoot {   
+          defconfig = "xilinx_zynq_virt_defconfig";
+          preConfigure = ''
+            export DEVICE_TREE=zynq-zc706
+          '';
+          extraMeta.platforms = ["armv7l-linux"];
+          filesToInstall = ["u-boot.elf"];
+        };
+
+        fsbl-sd = pkgs.runCommand "${target}-fsbl-sd"
+          {
+            buildInputs = [ zynqpkgs.mkbootimage ];
+          }
+          ''
+            bifdir=`mktemp -d`
+            cd $bifdir
+            ln -s ${fsbl}/fsbl.elf fsbl.elf
+            ln -s ${u-boot}/u-boot.elf u-boot.elf
+            cat > boot.bif << EOF
+            the_ROM_image:
+            {
+              [bootloader]fsbl.elf
+              u-boot.elf
+            }
+            EOF
+            mkdir $out $out/nix-support
+            mkbootimage boot.bif $out/boot.bin
+            echo file binary-dist $out/boot.bin >> $out/nix-support/hydra-build-products
+          '';
+        in {
+          "${target}-fsbl-sd" = fsbl-sd;
+        };
+
+      in rec {
+      packages.x86_64-linux = {
+        zc706-fsbl = zynqpkgs.zc706-fsbl;
+      } // (build { target = "zc706"; });
       
-  outputs = { self, not-os }: {
       packages.armv7l-linux = let
         platforms = (import not-os.inputs.nixpkgs { config = {}; }).platforms;
         eval = (import "${not-os}" {